Digital inputs.

Forum 2005-2010 (read only) Hardware Interfacing
1

Hi! I'm building a board with a lot of buttons based in Arduino. The case is that it is limited to 14 port I/O, but we are interested only function as inputs. Is there a way to allow using more inputs?
I know there is the option of using a multiplexer, but that idea did not convince me and I just thought of another way:

Connect an X button to input 0.
Connect an Y button to input 1.
Connect an Z button to input 0 and input 1.

I think I could differentiate when I pressed the X, Y or Z, don't?
THANKS!

2

No you have problems when two buttons are pressed down at the same time. Also you are connecting two inputs together so you will never be able to see the single buttons. The trick is to use diodes.

Look into a scanning matrix for push buttons.
One example is the 65 buttons used on my monome project:-
http://www.thebox.myzen.co.uk/Hardware/Econo_Monome.html

But there are others google around.